Weight Station - Page 2

The Leanness Advantage

First, let's look at the physiological advantages of being a lean trail runner. The basic factor that determines our ability to run long and fast is our maximal oxygen uptake (aka VO2max), of which weight is a critical component. VO2max is measured by running on a treadmill in a lab to exhaustion while a measurement of our oxygen consumption at the end point is taken using a gas analyzer. Then, to measure our oxygen uptake relative to our individual body weight, this figure is converted to milliliters of oxygen and divided by our body weight, in kilograms. A good runner will have a VO2max over 65 mlsO2/kg, with elite distance runners and trail runners being over 70 mls/kg.

Although VO2max is to a large extent genetically determined, the lighter the runner, the higher the oxygen consumption per kilogram of body weight will be, and the faster the runner will be over ultra and trail runs. Being overweight also means that you have to expend extra calories to pull your body over the same distance, and the extra fat makes it harder for us to lose heat during our ultras.

Thus we are penalized for carrying extra weight, and when starting out the best thing the beginning trail runner can do is to lose weight to improve his or her VO2max. Fortunately, by doing lots of long-distance running, you can improve your VO2max significantly—between 15 and 25 percent in the first eight to 16 weeks, according to elite trail and ultrarunner Greg Crowther of Seattle, who has a Ph.D. in physiology and biophysics from the University of Washington. "The percentage improvement can change a lot, even as much as 50 percent over several years," says Crowther.

Crowther, who has raced 26 ultras ranging from 50 kilometers to 100 miles, finishing 24 and winning 11, says, "I improved my time at the White River 50 by about four minutes from 2009 to 2010, partly because I was about four pounds lighter. Extra weight is also an issue for up- and downhill running, when the quadriceps are under extra stress from the eccentric contractions. Anything that you can do to minimize this stress, including weighing no more than necessary, should help reduce muscle damage."

Running Versus Other Aerobic Activities

Next, let us compare running with the other major aerobic activities in the calorie-burning sweepstakes. See the accompanying sidebar for a ranking of the most common aerobic sports in descending order of calorie burn (biggest burners at the top).

Running is the heaviest calorie burner, ranking over cross-country skiing, lap swimming, rowing and cycling. Trail running would rank in the top three categories, because of the constantly changing terrain and the extra calories being burned by the stabilizer muscles that enable us to negotiate trails' twists and turns.

This is all encouraging, but take a look at the fine print in the final column and you will see that burning large amounts of calories requires long and intense workout levels. For example, you would have to run roughly 8 mph (7.5-minute miles) for one hour to burn 1100 calories—somewhat discouraging when you consider that a 1000-calorie burger can be eaten in 10 minutes!

Also, these paces and distances are beyond the range of the beginning or overweight runner. The high-intensity requirement makes it almost impossible for recreational runners to employ a running program for effective weight loss, and overweight people are at an even greater disadvantage because they are more likely to experience muscle soreness and injury than normal weight people, because of their excess weight. While overweight people tend to lose weight faster than normal weight people, especially in the early stages of exercise, they are simply not able to maintain the energy demands of training fast every day, and will inevitably end up exhausted, sick or injured.